There are existing methods to bond fluoroelastomers to substrate materials such as EPDM and Nitrile. However these methods have not proven successful in applications where the material is subject to significant stress, such as bending, perforating, doming, and stretching. In the waste water aeration market, for example, membranes are perforated and continuously stretched and flexed. The method of connecting multiple layers must be a strong and permanent one to survive this kind of application.
It is well known that monopolymeric rubber membranes made non fluoroelastomers lack desirable chemical and physical properties of fluoroelastomers such as temperature resistance, mechanical and physical functions, and chemical resistance.
Likewise fluoroelastomers are limited in elongation, flexibility, strength, modulus, hardness and other physical properties.
Therefore the ideal combination adopts the desirable characteristics of both fluoroelastomers and non fluoroelastomers.
One specific example of an application for this technology is in the diffused aeration business, where perforated rubber membranes, submerged in either chemical or municipal waste water, are flexed continuously in order to produce a multitude of fine bubbles. The fine bubbles transfer oxygen efficiently from gas to liquid phase. Such membranes traditionally have been subject to attack by wastewater contents which are relatively common, such as fats, oils, greases, aromatic hydrocarbons, calcium carbonate deposits on the water side of the membrane, and ozone or oxygen attack on the air side of the membrane. Through the use of a multiple layered membrane it is possible to maintain the well established physical properties of today's EPDM membranes while adding a protective fluoroelastomer shield at an economical cost.